Conventionally, a technique of remotely operating an appliance to be controlled, such as an air conditioner, by means of radio communication with use of a mobile terminal such as a smartphone has been proposed. For example, Japanese Unexamined Patent Application Publication No. 2003-284162 discloses that an operation mode of an appliance to be controlled is changed according to whether or not connection of radio communication between the appliance to be controlled and a mobile terminal is established.